Gas burner

ABSTRACT

A gas burner for heating a stream of moving air in a duct. The burner body comprises a continuous peripheral combustion mixing chamber extending into the path of relatively high-speed air which is generated in the duct off the tips and the outer portions of the blades of a propeller-type fan forcing air through the duct. An air control sleeve comprises the central portion of the burner body in the path of relatively lower velocity air in the moving stream which is generated by the central portions of the blades.

United States Patent lnventors Guy R. Harter New Castle; Harry R. Maxon, Jr., Muncle, both of 1nd. Appl. No. 17,775 Filed Mar. 9, 1970 Patented Dec. 7, 1971 Assignee Maxon Premlx Burner Company, Inc.

Muncle, 1nd.

GAS BURNER 3 Claims, 5 Drawing Figs.

1.1.5. Cl 263/19 A Int. Cl. F231 9/04 Field 01 Search 263/ I 9; l 26/ l 10 C [56] References Cited UNlTED STATES PATENTS 3,055,145 9/1962 Lindsay 263/19 X 3,057,61 1 10/1962 Bjerkan 263/19 A R e 2 5,6 26 7/1964 Yeo et a1. 263/19 A 3,193,265 7/1965 Cowan 263/19 A Primary Examiner- Edward G. Favors Attorney-Hume, Clement, Hume 8L Lee ABSTRACT: A gas burner for heating a stream of moving air in a duct. The burner body comprises a continuous peripheral combustion mixing chamber extending into the path of relatively high-speed air which is generated in the duct off the tips and the outer portions of the blades of a propeller-type fan forcing air through the duct. An air control sleeve comprises the central portion of the burner body in the path of relatively lower velocity air in the moving stream which is generated by the central portions of the blades.

PATENTEDIPEB 1m 3,625495 SHEET 2 0F 2 J/a/rr J2. wa on, Jr:

GAS BURNER The present invention relates generally to gas burners. More particularly, the invention relates to a gas burner particularly designed to match the quality of the airstream in which it functions.

The invention comprises a gas burner adapted to be disposed in a duct wherein air is moving at a relatively higher velocity at the peripheral portions of the duct, and at a relatively lower velocity at the central portion of the duct. It has been observed that when a propeller-type fan is used to generate the movement of air in a duct, the greatest velocity of air is directed in a ring off the tips and the outer portions of the blades. As a result, a stream of relatively higher velocity air is generated in the peripheral portion of the duct, while a slower moving stream of air passes through the central portion of the duct for some limited distance downstream from the fan. A gas burner using the rapidly moving air in the duct for combustion will operate at greater efficiency and produce more uniform temperature distribution downstream than if the slower velocity air were mixed for combustion. Hence, a gas burner with combustion mixing air intake ports located substantially in the path of the higher velocity air is preferable to prior gas burner assemblies comprising a center feed and petals or wings" radiating outward therefrom.

Therefore, it is an object of the present invention to provide a gas burner adapted to be disposed in a duct wherein only relatively high-velocity moving air is admitted to the combustion mixing portion of said gas burner.

Another object of the present invention is to provide a gas burner which will operate at optimum efficiency near a propeller fan producing moving air in a duct, wherein the burner is located close to the fan, thereby reducing the length of the heater.

It is a further object of the present invention to provide a gas burner wherein relatively slower moving air passes centrally through said burner and does not enter the combustion mixing portion of said gas burner.

Another object of the present invention is to provide a gas burner having a combustion mixing portion wherein slower moving air passing centrally of said gas burner cools one wall of said combustion mixing portion.

An additional object of the present invention is to provide air control sleeve means disposed centrally of a gas burner wherein the length of said air control sleeve determines the temperature in the sleeve.

A further object of the present invention is to provide a gas burner designed to conform to the quality of an airstream in which said burner is functioning wherein stratification and overheating is avoided by providing uniform heat distribution as required to match varying air velocity across the airstream.

The novel features of the present invention are set forth with particularity in the appended claims. The invention together with further objects and advantages thereof may best be understood, however, by reference to the following description taken in conjunction with the accompanying drawings in the several figures of which like reference numerals identify like elements and in which:

FIG. I is a fragmentary sectional view of a gas burner embodying the features of the present invention shown situated in a duct wherein air is moving from top to bottom, as illustrated;

FIG. 2 is a plan view of the gas burner taken along lines 2-- 2 of FIG. 1;

FIG. 3 is an enlarged detail view of the apertured plate forming one wall of the combustion mixing space of the gas burner illustrated in FIG. 1;

FIG. 4 is a fragmentary sectional view of an alternate embodiment of the gas burner of the present invention whereir'f the gas burner and the air duct in which it is situated are in the shape of a rectangle;

FIG. 5 is a plan view of the gas burner taken along lines 5 5 of FIG. 4.

Referring now to FIGS. 1, 2 and 3, there is illustrated a gas burner centrally disposed in a duct 12 having a circular circumference, through which duct a stream of air is moving from top to bottom. Air is being driven through duct 12 by means of a propeller-type fan blade 13. The blade 13 directs the greatest velocity of air through the duct 12 in a ring off its tips and the outer portions of the blade. As a result, the part of the airstream passing through duct 12 near its peripheral region is moving at a relatively high velocity compared to the portion of slower moving air passing through the central region of duct 12.

Gas burner 10 includes a fuel gas or mixture inlet pipe 14 attached to a suitable source of fuel gas (or gas-air mixture), not shown. Fuel gas is conveyed by pipe 14 to manifold section 16 forming a gas conduit. Manifold section 16 is a circular, continuous, tubular channel with a row of burner ports 18 extending therethrough and arranged at a series of points along the circular length of the manifold. Burner ports 18 are operable to discharge variable amounts of fuel gas in jets from manifold 16. lgniter means (not shown) are provided to produce a flame which is subsequently formed from the jets of fuel gas issuing from ports 18.

From the outer lower portion (as seen in FIG. 1) of manifold section 16, a conical-shaped mixing wall 20 is afiixed to and extends obliquely outward continuously around the circumference of manifold 16. The conical-shaped mixing wall 20, which may comprise one piece per side or many sections per side, contains a plurality of rows of spaced air-admitting apertures 22, desirably of progressively increasing size moving downstream. The outer extent of mixing wall 20 is provided with a stiffening flange 24 which cooperates to maintain the shape and strength of mixing wall 20. Flange 24 also cooperates with the mixing wall 20 to protect the gas flame from the high-velocity air as the flame issues from mixing space 28. Further, flange 24 assists in producing turbulence, which creates intermixture of the hot combustion gases and high-velocity air downstream of gas burner 10.

Afflxed to the inner circumference of manifold section 16 on the opposite side of burner ports 18 from mixing wall 20 is a substantially imperforate wall 26 forming an annular air control sleeve 27 centrally of burner assembly 10. Wall 26 extends from manifold section 16 to a point downstream of burner assembly 10, which point is established pursuant to desired heating conditions, as will be explained.

As best seen in FIG. I, immediately forward of burner ports 18, mixing wall 20 and wall 26 fonn an annular, continuous, forwardly widening semitrough-shaped combustion mixing space 28. Mixing wall 20 extends into the path of high-velocity air moving in the peripheral region of duct 12, and jets of air are produced by the air which is allowed to enter space 28 through apertures 22. The slower moving air moving through air control sleeve 27 normally does not enter space 28 because of the lack of a measurable degree of perforations in wall 26. However, if a measurable degree of perforation were provided in wall 26, slower moving air may be permitted entry into space 28.

The air in duct 12 is flowing in the direction indicated by the arrows (FIG. 1). As previously described, the air is moving at a relatively high velocity near the peripheral region of the interior of duct 12, while moving at a relatively lower velocity through the central region of duct 12.

The higher velocity air approaches the burner unit from the back side of manifold 16 and will flow forward along the outer face of mixing wall 20. The open mouth of combustion mixing space 28 faces downstream in the direction of airflow, and airflow past the outer periphery of burner assembly 10 and the downstream edge of space 28 will create a low pressure, or vacuum, in combustion mixing space 28. This vacuum, plus the ram effect of air through the apertures 22 will cause jets of air to issue obliquely inward through apertures 22 into combustion mixing space 28. These jets will be insufficient to satisfy the vacuum within combustion mixing space 28; moreover, they will themselves induce low pressure in the areas around and between the jets and adjacent the inner faces of mixing wall 20. These low pressure areas between the jets will provide flow paths into which gas issuing from manifold 16 through burner ports 18 will be drawn into combustion with the air. Gas will also flow along these paths when the gas is not completely consumed in flames at the burner ports I8 and unburned gas is present in sufficient quantities to permit that flow to occur. The gas flow in such low pressure paths can carry gas to all the air jets issuing through the apertures 22 in mixing wall 20.

The slower moving air passing through the center portion of duct 12 passes through the open central portion of manifold 16 and through the air control sleeve 27 formed by substantially imperforate wall 26. This slower moving air, which is not burned as is the air in combustion mixing space 28, moves downstream along wall 26 and is shielded from coacting with the gas in combustion mixing space 28. Due to the lower temperature of this slower moving, unburned air, in relation to the temperature of the combusted air in space 28, the air passing through sleeve 27 cools wall 26.

The length of the air control sleeve 27 formed by wall 26 detennines the point of downstream mixing between heated and unheated air. As a result, the temperature created in the central regions of duct 12, and air control sleeve 27, may be controlled by varying the length of air control sleeve 27.

In the alternate embodiment illustrated in FIGS. 4 and 5, a gas burner 30 is situated in the interior of a rectangularshaped air duct 32. An airstream flows through the duct from top to bottom, as seen in FIG. 4, driven by a propeller-type fan blade 33. As stated in describing the initial embodiment, the propeller blade 33 directs the greatest velocity of air off the tips and outer portions of the blade. As a result, the air of relatively high velocity passes through duct 32 at its peripheral region, while relatively slow velocity air passes through the central region of duct 32.

Burner assembly 30 includes a fuel gas or mixture inlet pipe 34 attached to a suitable source of fuel gas (or gas-air mixture) not shown. Fuel gas is conveyed by pipe 34 to manifold 36 forming a gas conduit. Manifold 36 is a rectangularly conformed continuous, tubular channel with a row of burner ports 38 arranged at a series of points along the rectangular length of the manifold. Manifold 36 may be constructed from a series of right-angled, open-ended, manifold sections, as shown in FIG. 5. Such manifold sections may be joined together by means of bolts 40 passing through mating flanges 41 located at the extremities of each open-ended manifold section.

Afflxed to the inner edge of manifold 36 on the opposite side of burner ports 38 from mixing wall 42 and extending around the entire rectangular length of manifold 36, is a substantially imperforate wall 48 forming a rectangular air control sleeve 49 centrally disposed in burner assembly 30. Wall 48 extends from manifold 36 to a point downstream of burner assembly 30 which point is established pursuant to desired heating conditions, as will be explained.

Immediately downstream of burner ports 38, mixing wall 42 and wall 48 from a rectangular, continuous, forwardly widening semitrough-shaped combustion mixing space 50. Apertures 44 in mixing wall 42 permit jets of air to flow from the relatively higher velocity portion of moving air into space 50. Air control sleeve 49 directs the slower velocity air through the central portion of burner assembly 30, and prevents a major portion of the slower velocity air from entering combustion mixing space 50.

It will be readily apparent to one skilled in the art that the operation of the rectangular burner assembly disclosed in FIGS. 4 and is similar to the operation of the circular burner disclosed in FIGS. 1 and 2, the only difference being that the former is designed to heat air flowing through a rectangular duct. Therefore, like parts disclosed in FIGS. 1 and 2 operate in a similar manner to like parts disclosed in the embodiment of FIGS. 4 and 5.

The present invention provides a gas burner which is designed to match the burner operation of the characteristics of the airstream in which it functions. As the shape of the airstream changes in shape or other characteristic, the gas burner may be adapted to conform to the change in airflow pattern without deviating from the scope of the appended claims to provide greater efficiency of combustion.

While particular embodiments of the present invention have been shown and described, it is apparent that various changes and modifications may be made, and it is therefore intended in the following claims to cover all such modifications and changes as may fall within the true spirit and scope of this invention.

Iclaim:

l. A gas burner adapted for operation in a duct having a moving airstream passing therethrough comprising:

a peripheral burner body defining a fuel gas supply passage;

gas port means provided at a series of points along the length of said burner body;

mixing plate wall means adjacent the outer side of said gas port means extending obliquely forward and outward from said burner body;

second wall means adjacent the inner side of said gas port means extending from said burner body in a forward direction substantially parallel to the direction of airstream movement through said duct;

said mixing plate wall means and said second wall means extending continuously along the peripheral length of said burner body and defining a forwardly widening semitrough-shaped combustion mixing space forwardly of said gas port means;

said mixing plate wall projecting laterally of said burner body with its backface exposed to the airstream flowing past the burner;

a plurality of apertures in said mixing plate wall spaced longitudinally thereof and at different distances from said burner body;

said apertures arranged to admit air from the passing airstream into the mixing space;

said gas port means being operable to discharge variable amounts of fuel gas or mixture from said burner body to mix with said air in said mixing space.

2. A heating system comprising:

a duct;

rotating impeller means operable in said duct to force a stream of air to pass through said duct;

said air moving through said duct at a relatively high speed near the peripheral region of said duct and moving at a relatively slow speed near the central region of said duct;

a continuous burner body defining a fuel gas supply passage located in said duct in the path of said relatively highspeed air;

a central cavity formed in said burner body through which said relatively slow-speed air passes;

gas port means provided at a series of points along the length of said burner body;

mixing plate wall means adjacent the outer side of said gas port means extending obliquely forward and outward from said burner body;

second wall means adjacent the inner side of said gas port means extending from said burner body in a forward direction substantially parallel to the direction of airstream movement through said duct;

said mixing plate wall means and said second wall means extending continuously along the length of said burner body and defining a forwardly widening semitrough-shaped combustion mixing space forwardly of said gas port means;

said mixing plate wall projecting laterally outwardly from said burner body with its backface extending into the stream of said relatively high-speed air;

a plurality of apertures in said mixing plate wall spaced longitudinally thereof and at different distances from said burner body;

said apertures arranged to admit air from the relatively high-speed passing airstream into said combustion mixing space;

said gas port means being operable to discharge variable an air control sleeve having substantially imperforate wall amounts of fuel gas or mixture from said burner body to means disposed centrally of said gas burner wherein said mix with said air in said combustion mixing space. low-velocity portion of the moving airstream passes 3. A gas burner adapted to be disposed in a duct for heating through said air control sleeve and cools said substantially a stream of moving air having a relatively high-velocity por- 5 p q Wall means; and tion moving axially through a first region of said duct and a Perforatemlxmg P l means exfendlflg from said gas relatively low-velocity portion moving axially through a burner to define 531d substamlfiny P P second region of said duct; means a continuous forwardly widening semitroughsaid gas burner being disposed in said duct in the path of Shaped combustion mixing space forwardly of Said g said relatively high-velocity portion of the moving 0 humer' airstream; W 

1. A gas burner adapted for operation in a duct having a moving airstream passing therethrough comprising: a peripheral burner body defining a fuel gas supply passage; gas port means provided at a series of points along the length of said burner body; mixing plate wall means adjacent the outer side of said gas port means extending obliquely forward and outward from said burner body; second wall means adjacent the inner side of said gas port means extending from said burner body in a forward direction substantially parallel to the direction of airstream movement through said duct; said mixing plate wall means and said second wall means extending continuously along the peripheral length of said burner body and defining a forwardly widening semitrough-shaped combustion mixing space forwardly of said gas port means; said mixing plate wall projecting laterally of said burner body with its backface exposed to the airstream flowing past the burner; a plurality of apertures in said mixing plate wall spaced longitudinally thereof and at different distances from said burner body; said apertures arranged to admit air from the passing airstream into the mixing space; said gas port means being operable to discharge variable amounts of fuel gas or mixture from said burner body to mix with said air in said mixing space.
 2. A heating system comprising: a duct; rotating impeller means operable in said duct to force a stream of air to pass through said duct; said air moving through said duct at a relatively high speed near the peripheral region of said duct and moving at a relatively slow speed near the central region of said duct; a continuous burner body defining a fuel gas supply passage located in said duct in the path of said relatively high-speed air; a central cavity formed in said burner body through whIch said relatively slow-speed air passes; gas port means provided at a series of points along the length of said burner body; mixing plate wall means adjacent the outer side of said gas port means extending obliquely forward and outward from said burner body; second wall means adjacent the inner side of said gas port means extending from said burner body in a forward direction substantially parallel to the direction of airstream movement through said duct; said mixing plate wall means and said second wall means extending continuously along the length of said burner body and defining a forwardly widening semitrough-shaped combustion mixing space forwardly of said gas port means; said mixing plate wall projecting laterally outwardly from said burner body with its backface extending into the stream of said relatively high-speed air; a plurality of apertures in said mixing plate wall spaced longitudinally thereof and at different distances from said burner body; said apertures arranged to admit air from the relatively high-speed passing airstream into said combustion mixing space; said gas port means being operable to discharge variable amounts of fuel gas or mixture from said burner body to mix with said air in said combustion mixing space.
 3. A gas burner adapted to be disposed in a duct for heating a stream of moving air having a relatively high-velocity portion moving axially through a first region of said duct and a relatively low-velocity portion moving axially through a second region of said duct; said gas burner being disposed in said duct in the path of said relatively high-velocity portion of the moving airstream; an air control sleeve having substantially imperforate wall means disposed centrally of said gas burner wherein said low-velocity portion of the moving airstream passes through said air control sleeve and cools said substantially imperforate wall means; and perforate mixing plate wall means extending from said gas burner to define with said substantially imperforate wall means a continuous forwardly widening semitrough-shaped combustion mixing space forwardly of said gas burner. 